For reasons of decreasing volume and weight, increasing power density, improving portability and the like, three-dimensional (3-D) semiconductor structures have been developed. In addition, elements and spaces in a semiconductor device have continuously been shrunk. This may cause some problems. For example, smaller landing areas for connectors may lead to contact difficulty and mismatch, and thereby the relative resistances are increased. As such, various improvements for the semiconductor structures and the methods for manufacturing them are still desired.